A Passive Optical Network, PON, or a Wavelength Division Multiplexing PON, WDM-PON, may be employed as a transport network within a client network. A WDM PON network comprises active equipment (switches, lasers, etc) and passive elements such as fibre and wavelength splitters. An ODN refers only to the fibre infrastructure and passive elements.
FIG. 1a is a schematic overview of an exemplifying PON. In general and very simplified, a PON comprises an Optical Line Terminal, OLT, which is connected to a plurality of Optical Network Terminal, ONTs. In FIG. 1a, an OLT 160 is comprised in an ODN. FIG. 1 also illustrates the OLT 160 being connected to three ONTs 100a, 100b and 100c. The ONTs are in turn either incorporated with a host 170a and 170b or connected to a host 170c. The ODN is also referred to as a transport domain. There may be additional equipment and/or devices connected to the hosts 170a-170c and to the OLT 160 so that the equipment/devices connected to the hosts 170a-170c may communicate with equipment/devices connected to the ONT 160 by means of the ODN. Any additional equipment and/or devices connected to the hosts 170a-170c and to the OLT 160 are referred to as a client domain.
In one example, the hosts 170a-170c constitute a radio base station, RBS, or antenna, by means of which users may access the network and communicate with other equipment/devices. In another example, the host is a set-top-box. The host may be a combination of software and hardware. In still an example, the host is the point by which a user accesses services offered by an operator, which services are provided over the ODN.
It may happen that an operator may need to update, configure or perform maintenance functions on the ONTs in the ODN. In order to do so, one example is the operator accessing the host, via the ONT, and then access the ONT via the host. In order for the operator to access the host, the operator must know and “understand” the protocol used by the host. In a typical ODN, the number of ONTs is very big and each host connected to the respective ONTs need not employ the same protocol, making it very cumbersome for the operator to access the different hosts. Further, such a solution requires there to be a control interface between the ONT and the host. Looking at FIG. 1a, ONT3 100c does not have such a control interface with its host-C 170c wherein this solution does not even work.
When managing the WDM-PON, one solution to measure the performance of the WDM-PON is to inject Optical Time Domain Reflectometer, OTDR, pulses into the ODN. OTDR pulses may be employed to monitor the ODN but not to monitor the ONT nor to perform any configuration, updating or maintenance actions. It may be possible to make use of the OTDR function by complimenting it with protocol based facilities such as ONT Management Control Interface, OMCI, in Gigabit PON, GPON. However, such a solution would be client dependent and it would not be generically applicable to any service carried over the WDM-PON.
In case the ONT has Medium Access Control, MAC, capability, the OLT can manage the ONT via Ethernet Operation, Administration and Maintenance, OAM, OMCI or similar MAC based methods. The method to perform configuration, updating or maintenance actions of the ONT(s) will then be different for different network protocols, e.g. Ethernet, Common Public Radio Interface, CPRI, and subject to the availability and limitations of these client networks or protocols. Further, such an approach also assumes that OAM is triggered at the MAC layer.
Looking again at FIG. 1a, assume that Host-A 170a is an Ethernet based host. Then it is possible to use Simple Network Management Protocol, SNMP, User Datagram Protocol, UDP, or Ethernet to get access to ONT1 100a via the SNMP enabled host 170a. Further assume that Host-B 170b uses CPRI. Then the operator must use Radio Access Network, RAN, vendor specific CPRI OAM facilities on Host-B 170b in order to get access to ONT2 100b via Host-B 170b. This illustrates that it may become almost impossible to manage a vast plurality of ONTs being connected to different hosts using different protocols.